AGA Urges Cautious Management of Pancreatic Cysts

But most recommendations are "conditional" because of weak evidence.

Action Points

Updated recommendations developed by the American Gastroenterological Association (AGA) on management of asymptomatic pancreatic neoplastic cysts call for a conservative approach in many cases because most such cysts are not cancerous.

Note that MRI is the preferred surveillance imaging modality because MRI does not expose the patient to radiation, and it is better able to demonstrate the structural relationship between the pancreatic duct and associated cyst than CT.

Updated recommendations developed by the American Gastroenterological Association (AGA) on management of asymptomatic pancreatic neoplastic cysts call for a conservative approach in many cases because most such cysts are not cancerous.

"The management of patients with an incidentally detected pancreatic cyst is a significant clinical challenge," wrote Marcia Canto, MD, and Ralph Hruban, MD, of the Johns Hopkins University School of Medicine, in commenting on the new recommendations in Gastroenterology.

"With increased use of MRI and CT, we are faced with the growing need to decide which of the thousands of detected cysts are innocuous and which are potentially deadly."

In an effort to provide a strategy by which clinicians may identify the small minority of cysts with early invasive cancer or high-grade dysplasia -- or those which will develop them in the near future -- AGA authors developed 10 recommendations, all but one of which were listed as "conditional" because of very low-quality evidence.

The AGA suggests that patients with pancreatic cysts <3 cm without a solid component or a dilated pancreatic duct undergo MRI for surveillance in 1 year and then every 2 years for a total of 5 years if there is no change in cyst size or characteristics.

"We estimate that a cyst seen incidentally on MRI has a 10 in 100,000 chance of being a mucinous invasive malignancy and a 17 in 100,000 chance of being a ductal cancer," Santhi Swaroop Vege, MD, Mayo Clinic, Rochester, Minn., and colleagues wrote in Gastroenterology.

"The overall risk that an incidental pancreatic cyst is malignant is therefore very low."

MRI is the preferred surveillance imaging modality, the authors add, because MRI does not expose the patient to radiation, and it is better able to demonstrate the structural relationship between the pancreatic duct and associated cyst than CT.

The AGA suggests that pancreatic cysts with at least 2 high-risk features such as size ≥3 cm, a dilated main pancreatic duct, or the presence of an associated solid component, should be examined with endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA).

The relative increase in risk of malignancy in the presence of high-risk features may be substantial but because the baseline risk is so low, the absolute effect of these features is modest, the AGA authors pointed out.

"Nevertheless, we believe that if two of these features are present ... they should trigger further investigations to characterize the risk of malignancy more accurately," they stated.

This is best achieved by endoscopic ultrasonography (EUS) and fine-needle aspiration (FNA) they add, with a sensitivity of about 60% and a specificity of about 90%.

The AGA suggests that patients without concerning EUS-FNA results should undergo MRI surveillance after 1 year and then every 2 years to ensure no change in risk of malignancy.

As the authors point out, the negative predictive value of unremarkable EUS-FNA results is very high and this in a setting with a very low risk of associated malignancy.

Certain exceptions might apply to a minority of patients in whom surgery is appropriate or surveillance with MRI earlier than 1 year should be done.

The AGA suggests that significant changes in the characteristics of the cyst including the development of a solid component, increasing size of the pancreatic duct, and/or diameter ≥3 cm, are indications for EUS-FNA.

The authors noted that they cautiously recommend reassessing patients who have these features during follow-up but that evidence to do so is weak.

The AGA suggests against continued surveillance of pancreatic cysts if there has been no significant change in the characteristics of the cyst after 5 years of surveillance or if the patient is no longer a surgical candidate.

The authors again cautioned that some patients may elect to continue surveillance for longer after discussion with their physician if other factors such as a strong family history of pancreatic cancer are present.

The AGA suggests that patients with both a solid component and a dilated pancreatic duct and/or concerning features on EUS and FNA should undergo surgery to reduce the risk of mortality from carcinoma.

"Normally, we would have given this a strong recommendations," AGA authors stated.

To do so, however, assumes that most patients will benefit from surgery.

In their review of the literature, the AGA authors determined that only about 28% of patients with invasive pancreatic cancer will still be alive at 5 years, and it may well be a much smaller proportion due to lead time bias.

"Surgery is likely to be most beneficial in cases of cyst resection of high-grade dysplasia, thereby preventing malignancy," they wrote.

Since it is clear from other cancers that not all high-grade dysplasia progress, "the proportion of patients who truly benefit from surgery is unclear even in this high-risk group," they added.

With a postoperative mortality rate of 2% and a very high morbidity rate, any benefit from surgery may again be mitigated.

The AGA recommends that if surgery is considered for a pancreatic cyst, patients are referred to a center with demonstrated expertise in pancreatic surgery.

This recommendation is self-evident, as the authors suggested, as postoperative mortality rates range from a low of 2% in centers of excellence to approximately 7% in less experienced institutions.

The AGA suggests that patients with invasive cancer or dysplasia in a cyst that has been surgically resected should undergo MRI surveillance of any remaining pancreas every 2 years.

The authors pointed out that physicians may elect to offer more frequent surveillance in patients who have undergone resection of invasive cancer, particularly if there is a concern that the lesion was not fully resected.

The AGA recommends against routine surveillance of pancreatic cysts without high-grade dysplasia or malignancy at surgical resection.

Continued surveillance in this group is extremely unlikely to be cost-effective, according to the guideline statement.

"The bottom line is that, even with imperfect radiologic diagnoses, the vast majority of asymptomatic cysts are low risk and ultimately will prove to be not lethal," Canto and Hruban wrote. "The AGA recommendations are unique and, [while] admittedly at times not based on strong evidence, are potentially practice changing."

The 10 recommendations also included a "motherhood statement" as follows:

The AGA recommends that before starting any pancreatic cyst surveillance program, patients should have a clear understanding of programmatic risks and benefits.

"When the probability of a cyst becoming malignant is explained to them, patients may elect not to undergo surveillance," the statement authors wrote.

"When the probability of a cyst becoming malignant is explained to them, patients may elect not to undergo surveillance," the statement authors wrote. They also noted that patients who have a limited life expectancy are unlikely to benefit from surveillance, which is inappropriate as well for those who are not surgical candidates because of age or severe comorbidities.

AGA authors had no conflicts of interest to disclose.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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